Current construction of automobile doors includes a plastic shell with various openings for door lock connections, electric window control buttons, ash trays, door handles and the like. To enhance the decorative appearance of the inside of doors which incorporate the plastic shell a decorative, fabric covered panel is adhered to the inside of the door. The current way to attach the decorative panel to the door is by way of "toy tabs" which are well known in the industry. Toy tabs are tabs or prongs struck from a metal sheet, the tabs are to project through holes in a substrate and be deformed to one side to lock the metal sheet to the substrate.
The way the toy tab structure is affixed to the decorative panel is by a bonding of the metallic layer at the unexposed face of the panel with the rearwardly projecting tabs pre-cut for later manipulation.
The decorative panels themselves are a sandwich of various materials including the aforementioned decorative layer on the front and the metallic layer bonded to the back.
Smith U.S. Pat. No. 3,234,064 and Scholl U.S. Pat. Nos. 3,520,755 and 3,655,477 et al show the manufacture of a composite piece of foamed materials and non-foamed covers to form a panel.
Polk U.S. Pat. No. 3,466,214 et al illustrates a way of forming a panel from composite material in a mold with the edge or ridge around the mold including a sharp cutting edge which cuts the product to the desired shape, note particularly FIG. 4. Similar structure in slightly modified form is illustrated in Hoyer U.S. Pat. No. 3,075,862.
Braun U.S. Pat. No. 3,355,345 illustrates a mold in FIG. 6 which shows a plurality of product molds on one sheet to be used in a press.
Hammond U.S. Pat. No. 4,350,734 illustrates a composite structure forming a rigid panel which uses one or more layers of open celled polyurethane foam in forming the panel.
It is noted that none of these cited patents includes a metal sheet as the back layer of the laminated panel.
The conventional door panel using the metal backing layer has many defects from a manufacturing and efficiency standpoint. One problem is that once the metallic backing layer becomes deformed it never quite fits or looks quite right when reshaped to a planar surface. Therefore, in the manufacturing and shipping of the panels it is critical that they be shipped so that a bend is not applied to the panel.
Another defect is the tab connection between the plastic door shell and the decorative panel. In order to be properly manipulable by the workman, the tabs projecting from the metal layer must not be too stiff. Conversely, in order that the door panel not work loose as a result of hundreds of door openings and closings, the tabs cannot be too flexible. A balance must be struck but it is inherent that the balance will not always work under all circumstances.
What is needed is a panel of sufficient rigidity as to serve the purpose of the door panel, which will not have a crease problem upon bending and which will not be subject to thermal expansion and contraction problems nor flexing problems from door openings and closings which could result in the separation of the panel from the plastic door shell.
While the above discussion has been directed specifically to automobile door panels, it will be quite obvious that the panels described previously and subsequently are not at all limited to automobile doors.